The development of interventions to maximize consistency in ultraviolet radiation (UVR) protection rests on improved understanding of decision-making factors that contribute to daily variation in UVR protection. In this study, we use Ethnographic Decision Tree Modeling to examine decision-making regarding sunscreen use, shade-seeking, and UVR protection behavior in melanoma first-degree relatives (FDRs). In Phase I, we will generate the models via qualitative ethnographic interviews with 25 melanoma FDRs, and then will construct a composite decision-making model for each of the three UVR protection outcomes. In Phase II we will establish the validity of the models using ecological momentary assessment of UVR protection (over 14 summer days, at 1 pm and 5 pm daily) in 60 FDRs. We will recruit equal numbers of women and men, and equal numbers of those who perceive high and low advantages of tanning, given the importance of these predictors for UVR protection. Specific Aim I is to generate and establish the validity of the models explaining decision-making about three UVR protection behaviors (sunscreen use, shade-seeking, use of protective clothing) in melanoma FDRs, and Specific Aim II is to examine theory-driven affective and cognitive predictors of sun protection maintenance (sunscreen use, shade-seeking, and use of sun protective clothing) assessed in real time. We adopt a theory-informed approach to decision-making, and so expect that the factors identified inductively in Phase I, as well as between- and within-subject variation in melanoma threat, efficacy beliefs, and satisfaction with UVR protection drawn from Witte's Extended Parallel Processing Model and Rothman's theory of health behavior maintenance will predict UVR protection behaviors. We will also examine gender and tanning attitudes as covariates of these effects. The study findings will increase our understanding of the decision- making context for behavioral maintenance of UVR protection, and dictate novel intervention strategies to reduce behavioral inconsistency - and increase behavioral maintenance - of UVR protection in those at high risk for melanoma. PUBLIC HEALTH RELEVANCE: This study will examine daily UVR protection and decision-making about protection in 60 first degree family members of melanoma patients who complete 14-day diaries via personal digital assistants and audio-taped narratives. We will employ qualitative and quantitative research strategies and determine between and within- person variability in UVR protection and decision-making that will inform the development of interventions to increase UVR protection maintenance among those who are at risk for melanoma.